Q: Can we replace GFRP rebar in ONE to ONE ratio of Steel bar?
A: MST-BAR is three times stronger, but more flexible than steel rebar and it behave linear elastic to failure, therefore there is no yield point to be determined however the material can take significantly higher load. Engineers must follow the Codes and Standard for GFRP rebar and not Steel. In most cases where serviceability is not governing the design and it is based on Ultimate Limit State(ULS) you can simply substitute your steel to MST-BAR High modules. If serviceability is governing the design then it is recommended to do proper engineering to ensure all the deflections are controlled.
Q: What is the difference between GRADE I, GRADE II and GRADE III GFRP Rebar?
A: MST Rebar Inc. manufacture MST-BAR as GRADE III according to CSA, Grade refers to modulus of elasticity of GFRP rebar. MST Rebar Inc only produces #3(10M) in Grade 1 for flatwork application. The remining sizes are all in Grade III.
· GRADE I - E > 40GPa
· GRADE II - E > 50GPa
· GRADE III - E > 60GPa
Q: Can we use MST-BAR rebar in active seismic regions(earthquake)?
A: YES, MST-BAR bars can be used as reinforcement in concrete subjected to seismic loading conditions. MST-BAR is capable of resisting reversal tension-compression cycles without failure. The large deformation, exhibited by GFRP material, allows the GFRP reinforced building to adequately dissipate the seismic energy. Currently more than 100 bridges and structures are reinforced with GFRP rebar in seismic regions. Although it has not been part of the code but there is no limit of why MST-BAR can not be used in seismic regions.
Q: What design guidelines should designer follow?
A: There are number of design guidelines available from CSA & ACI.
· CAN/CSA-S6-06(Canadian highway bridge design code)
· CAN/CSA-S806-02(Design and construction of building component with FRP)
· ACI 440.1R-06
· ACI 440R-07
· ACI 440.5-08
· ACI 440.6-08
· AASHTO GFRP-1